Red-faced city officials mistakenly sent notices threatening to suspend the pensions of 1,157 retired teachers – for a whopping 200 years – allegedly for double dipping.

“Your retirement allowance should have been suspended for a total of 2,400 months,” the New York City Teachers’ Retirement System told frightened pensioners in a letter dated Wednesday.

Under state law, retirees are barred from earning more than $15,500 from another government job while collecting a pension. Anyone who exceeds the limit would have their pension suspended – but only for less than a year.

Sensing a snafu, 335 frightened and raving-mad retired educators blitzed the office’s phone lines complaining about the letters. Retirees – and even their offspring – would never see another penny of pension income under such a severe penalty.

But the 2,400-month suspension figure is not all the retirement system got wrong.

Retiree Ellen Tittler – who taught for 33 years at Brandeis and Prospect Heights high schools – told The Post the pension agency claimed she earned more than double the $15,500 limit in employment income after she retired in July 1999.

But Tittler produced tax records showing she earned only $1,100 as a ballroom-dancing instructor for a private company that year.

She said retirement officials goofed by calculating her teacher-salary income that she earned earlier that year – before she retired – against her pension.

“I was terrified that my income was going to be suspended by bureaucratic bungling and that I would have no control over the situation,” Tittler said.

“I’m just infuriated by this. It’s crazy.”

Pension officials admitted the goof and said they will immediately send corrected letters to all 1,157 retirees.

“It’s a system error. We don’t know what caused it,” said Jonathan Kimmel, legal director of the teachers’ retirement system.

“An apology letter is going out on Monday assuring them that their retirement allowance will not be suspended.”

Kimmel said pension officials will investigate whether other mistakes were made in individual cases like Tittler’s.